The present invention relates to a matrix printer particularly a matrix line printer having a reciprocating carrier or shuttle carrying the printing elements such as hammers or styli and including electromagnets for actuating the print elements.
Matrix printers of the type to which the invention pertains are usually used as data output devices having to deal with a rather high volume of date to be outputted. In addition or alternatively, they serve in word processing equipment permitting high quality or letter quality printing, for example, for correspondence or the like. A printer of the type to which the invention pertains is, for example, disclosed in U.S. Pat. No. 3,999,644 (see also German printed patent application No. 22 24 116). In this particular printer a shuttle or carriage is provided with a relatively large number of electromagnets each moving a printing needle or stylus in the direction toward the printing platen. The rear ends of these electromagnets are provided with a requisite connection which include a flexible cable for connection to a logic circuit which in turn is selectively driven by means of a character generator. Typically the printer may be equipped with about 33 electromagnets, requiring accordingly 66 cable connections.
Aside from the number of the cable connections involved a disadvantage is the fact that the carrier for the electromagnets does move so that the connections have to be moved too. The speed as well as acceleration of the shuttle is quite high so that the electromagnets have to be firmly secured to the carrier in a durable fashion wherby in addition particular features are required to insure equidistant spacing between the needles and a very accurate transverse orientation to the printing platen as well as to the recording medium on the platen. Accordingly, the known devices deem a particular fastening structure to be required as, for example, described in particularity in German Pat. No. 24 24 629.
The device disclosed in this German patent includes a bar-shaped carrier being provided with a plurality of holding devices arranged laterally and in juxtaposed position. An electromagnet constituting a unit is fastened thereto and arranged thereon together with the printing needles and their guidance structure. Each holding structure, moreover, is included with a semi-cylindrical seat for receiving the electromagnet, and there is a back provided for the bearing and guidance of the printing needles. All these aspects render the bar-shaped carrier heavy and expensive. Not only is the construction as such expensive but the relative high weight requires correspondingly high moving forces. All this is effective in some fashion on other modules and components or component groups within the printer. As a consequence the electric drive mechanism and the support for the bar-shaped carrier are expensive and have to be rated higher as far as dimensions are concerned than would be necessary strictly from a funcitonal point of view.
For physical reasons one can see that it is not a good solution to increase the mass of the bar-shaped carrier carrying the electromagnets and to increase the weight of the overall carriage through a particular fastening structure. In addition, of course, there has to be considered that another drawback is the increase in weight on account of the cable connection. Moreover the life of electric conductors is limited in any event.